On the fly transcoding of video on demand content for adaptive streaming

ABSTRACT

A method includes receiving a request at a media server from a computing device for a portion of a particular rendition of content that is available for adaptive streaming. The request received while the media server has access to a single rendition of the content. When the portion is part of the single rendition, the media server sends the portion retrieved from the single rendition to the computing device in response to the request. When the portion is not part of the single rendition, the media server generates the portion by transcoding a corresponding portion of the single rendition of the content, stores the generated portion in a cache of the media server, and sends the generated portion to the computing device in response to the request. The method further includes removing portions of one or more outdated renditions from the cache while maintaining the generated portion in the cache.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims priority to U.S.patent application Ser. No. 13/842,207, filed Mar. 15, 2013 and entitled“ON THE FLY TRANSCODING OF VIDEO ON DEMAND CONTENT FOR ADAPTIVESTREAMING”, the content of which is incorporated by reference in itsentirety.

BACKGROUND

The popularity of the Internet, coupled with the increasing capabilitiesof personal/mobile electronic devices, has provided consumers with theability to enjoy multimedia content almost anytime and anywhere. Forexample, live (e.g., sports events) and video on demand (VOD) content(e.g., television shows and movies) can be streamed via the Internet topersonal electronic devices (e.g., computers, mobile phones, andInternet-enabled televisions).

For example, content can be streamed from a content source to adestination device. Due to the variety of device types, device sizes,and encoding technologies available to consumers, making a particularcontent item available for streaming may involve storing multiplereplicas of the content item (each replica specific to a device type, adevice size, and/or an encoding technology). Storage and management ofthe replicas may be further complicated when adaptive streaming issupported. Adaptive streaming enables a media player to requestdifferent versions of a media stream in response to changes in networkconditions. To support adaptive streaming, each replicated version of acontent item may be broken down into multiple parts that are key framealigned. Thus, to offer adaptive streaming of a single content item tomultiple types of devices, a content provider may need to store andmanage hundreds or even thousands of files.

SUMMARY

Systems and methods of performing on the fly transcoding of video ondemand (VOD) content are disclosed. The ability to perform transcodingon the fly may simplify storage and management involved with supportingadaptive streaming of VOD content. In accordance with the describedtechniques, a media server may store only a single rendition of a videoon demand (VOD) item (e.g., a television show, a movie, etc.). Thestored rendition may correspond to a “best available” version (e.g.,highest available bitrate, aspect ratio, etc.) of the VOD item. Eventhough the media server stores only the single rendition, the mediaserver offers multiple renditions (e.g., bitrates) of the VOD item foradaptive streaming. When the media server receives a request for aportion of a particular rendition of the VOD item, the media servergenerates the requested portion of the requested rendition on the fly bytranscoding a corresponding portion of the stored rendition of the VODitem. It will be appreciated that by generating requested VOD itemportions on the fly, the amount of storage required to implementadaptive streaming of VOD content may be reduced significantly.

The media server may optionally utilize a caching mechanism totemporarily store portions of the VOD item that are generated on thefly. The caching mechanism may enable the cached portions to be re-used(without performing another transcoding operation) if the same bitrateis requested later.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram to illustrate a particular embodiment of a systemthat is operable to perform on the fly transcoding of VOD content foradaptive streaming;

FIG. 2 is a diagram to illustrate a particular example of transcodingtemplates used by the system of FIG. 1;

FIG. 3 is a flowchart to illustrate a particular embodiment of a methodof performing on the fly transcoding of VOD content for adaptivestreaming; and

FIG. 4 is a flowchart to illustrate another particular embodiment of amethod of performing on the fly transcoding of VOD content for adaptivestreaming.

DETAILED DESCRIPTION

FIG. 1 is a diagram to illustrate a particular embodiment of a system100 that is operable to perform on the fly transcoding of video ondemand (VOD) content for adaptive streaming. The system 100 includes amedia server 150. The media server 150 is configured to send and receivedata from various other devices (e.g., via a network, such as a localarea network (LAN) or the Internet). For example, the media server 150may communicate with one or more playback devices 170 (e.g., devicesthat are configured to stream VOD content) and one or more other servers180.

It should be noted that although various operations described herein aredescribed with reference to “video” on demand, this is for example only.The described systems and methods may also be used to perform on the flytranscoding of audio items. Thus, the term “video on demand” includesaudio-only, video-only, and audio-video content.

The media server 150 may include one or more processors 151 and variouscomponents that are executable by the processor(s) 151. The media server150 may correspond to software application(s) that perform media servingor processing, hardware systems (e.g., servers) that support or performmedia serving and processing, or any combination thereof. Thus, variousoperations described with reference to the media server 150, orcomponents thereof, may be implemented using hardware, software (e.g.,instructions executable by the processor(s) 151), or any combinationthereof.

The media server 150 may include one or more network interfaces 152. Forexample, the network interface(s) 152 may include input interface(s) andoutput interface(s) that are configured to receive data and to senddata, respectively. In a particular embodiment, the network interface(s)152 may be wired and/or wireless interfaces that enable the media server150 to communicate data via a network, such as the Internet. Forexample, the network interface(s) 152 may include an Ethernet interface,a wireless interface compatible with an Institute of Electrical andElectronics Engineers (IEEE) 802.11 (e.g., Wi-Fi) protocol, or otherwired or wireless interfaces.

The media server 150 may also include one or more encoders 153, decoders154, and transcoders 155, each of which may be implemented usinghardware or software. For example, one or more of the encoder(s) 153,decoder(s) 154, and transcoder(s) 155 may be implemented using Javaclasses (e.g., executable by a Java Virtual Machine (JVM)), C++instructions, C instructions, etc. The decoder(s) 154 may decode datareceived by the media server 150. For example, the decoder(s) 154 maydecode received streams (e.g., live audio-only, video-only, oraudio-video streams) and files (e.g., VOD items). The encoder(s) 153 mayencode data that is to be transmitted by the media server 150. Theencoder(s) 153 and decoder(s) 154 may thus enable the media server 150to process data in accordance with multiple coding technologies andprotocols.

For example, the media server 150 may support video encoding typesincluding, but not limited to, H.264, On2 VP6, Sorenson Spark, Screenvideo, Screen video 2, motion picture experts group (MPEG) 2 (MPEG-2),and MPEG-4 Part 2. The media server 150 may support audio encoding typesincluding, but not limited to, advanced audio coding (AAC), AAC lowcomplexity (AAC LC), AAC high efficiency (HE-AAC), G.711, MPEG AudioLayer 3 (MP3), Speex, Nellymoser Asao, and AC-3.

The media server 150 may support communication (e.g., adaptive streamingand non-adaptive streaming) protocols including, but not limited to,hypertext transfer protocol (HTTP) live streaming (HLS), HTTP dynamicstreaming (HDS), smooth streaming, and MPEG dynamic adaptive streamingover HTTP (MPEG-DASH) (also known as international organization forstandardization (ISO)/international electrotechnical commission (IEC)23009-1). The media server 150 may also support real time messagingprotocol (RTMP) (and variants thereof), real-time streaming protocol(RTSP), real-time transport protocol (RTP), and MPEG-2 transport stream(MPEG-TS). Additional audio formats, video formats, coder/decoders(CODECs), and/or protocols may also be supported.

The media server 150 may include non-volatile storage 158 (e.g.,disk-based storage device(s)). In a particular embodiment, thenon-volatile storage 158 may store a single rendition 110 of a VOD item.As used herein, a “rendition” of a VOD item may correspond to aparticular version of the VOD item. Each rendition of a VOD item mayhave a distinct bitrate (e.g., video bitrate and/or audio bitrate).Renditions may also differ from each other with respect to other audioand video quality parameters, such as frame size, frame rate, videocoder/decoder (CODEC), audio CODEC, number of audio channels, etc. In aparticular embodiment, the stored rendition 110 is a “best available”version of the VOD item. For example, as shown at 111, the media server150 may receive the rendition 110 from an external source, such as acontent provider, where the rendition 110 is the highest-quality versionof the VOD item that is available. To illustrate, the rendition 110 maybe a high-definition (HD) rendition with a 1980×1024 pixel resolutionand 5.1 or 7.1 channels of audio. It should be noted that although arendition of only a single VOD item is shown in the non-volatile storage158, this is for example only. The non-volatile storage 158 may store asingle rendition of multiple VOD items, and the media server 150 maysupport adaptive streaming of multiple VOD items to multiple playbackdevices, as further described herein.

The transcoder(s) 155 may be configured to transcode the storedrendition 110 of the VOD item, or portions thereof, to generateadditional renditions (or portions thereof). For example, thetranscoder(s) 155 may transcode the high-quality stored rendition 110 togenerate lower-quality renditions of the VOD item that are suitable forstreaming in low-bandwidth network conditions. The transcoder(s) 155 maybe configured to perform bitrate conversion, CODEC conversion, framesize conversion, etc. Moreover, such transcoding may be performed on thefly (e.g., just-in-time) in response to requests from playback devices.Thus, the media server 150 may be able to generate multiple renditionsof VOD items on the fly, even though only a single rendition of each ofthe VOD items is stored in the non-volatile storage.

Depending on a format of the stored rendition 110, a playback formatsupported by a requesting device, and/or transcoding parameters in useby the transcoder(s) 155, a transcoding operation performed by thetranscoder(s) 155 may trigger a decoding operation by the decoder(s) 154and/or a re-encoding operation by the encoder(s) 153. In a particularembodiment, parameters used by the transcoder(s) 155 are stored in oneor more transcoding templates 156. For example, the transcodingtemplate(s) 156 may be computer-readable files (e.g., eXtensible markuplanguage (XML) files) that define transcoding parameters (e.g., bitrate,type of CODEC, etc.) for various stream renditions. An illustrativeexample of a transcoding template is further described with reference toFIG. 2.

During operation, the media server 150 may perform on the flytranscoding of VOD items for adaptive streaming Adaptive streaming is amedia transmission mechanism that enables a receiving device todynamically request different versions of a stream in response tochanging network conditions. For example, one of the playback devices170 (e.g., a desktop or laptop computing device 171, a television orset-top box 172, a smartphone 173, or a tablet computer 174) mayinitiate an adaptive streaming session with the media server 150 for aparticular VOD item. The media server 150 may send a manifest 120 to theinitiating device (e.g., the computing device 171). The manifest 120 mayinclude information describing each of a plurality of renditions of theparticular VOD item that are available for adaptive streaming. Forexample, the transcoding template(s) 156 may define each of theavailable renditions, as further described with reference to FIG. 2, andthe manifest 120 may be automatically generated based on the transcodingtemplate(s) 156. When the stored rendition 110 is one of the renditionsoffered for adaptive streaming, requests for portions of the storedrenditions are satisfied without performing transcoding. When the storedrendition 110 is not offered for adaptive streaming all requests forportions of the available renditions are satisfied using on the fly bytranscoding of a corresponding portion of the stored rendition 110, asfurther described herein. Thus, although multiple renditions (e.g.,bitrates) are described by the manifest 120 as being “available,” atmost only one of the available renditions is stored at the media server150.

In the example of FIG. 1, the manifest 120 describes four availablerenditions of the VOD item (illustrated in FIG. 1 by four arrows betweenthe media server 150 and the playback devices 170). However, it will benoted that only one of the arrows is solid, whereas the remaining arrowsare dashed. This is to indicate that although four renditions are“available” only one of the renditions may be sent to a particularplayback device 170 at any given time. Different renditions of the sameVOD item may be sent to different playback devices at the same time. Inalternate embodiments, more than four renditions or less than fourrenditions may be available for adaptive streaming Upon receiving themanifest 120, the computing device 171 may determine which of theavailable renditions of the VOD item should be requested from the mediaserver 150. For example, the computing device 171 may make such adetermination based on buffering/processing capability at the computingdevice 171 and/or network conditions being experienced by the computingdevice 171.

Upon determining which rendition should be requested, the computingdevice 171 may transmit a request 130 to the media server 150. Therequest 130 may specify a particular portion (e.g., portion “X”) of therequested rendition. The particular portion may be specified usingstart/end frame numbers, start/end times, a portion number/identifier,etc. Depending on the adaptive streaming protocol in use, the requestedportion may correspond to a “chunk” of a rendition and/or a group ofpictures (GOP). A “chunk” may refer to a fixed (e.g., ten seconds) orvariable length duration of a stream rendition. A group of pictures mayrefer to a collection of video frames that includes one or moreintra-coded frames (I-frames) and one or more additional frames thatinclude difference information relative to the one or more I-frames(e.g., P-frame and/or B-frames). If there are no problems with receiptand playback of the requested portion, the computing device 171 mayrequest a subsequent portion (e.g., portion “X+1”) of the same renditionof the VOD item. However, if playback and/or network conditions becomeworse, the computing device 171 may switch to a lower bitrate renditionby requesting subsequent portions of the lower bitrate rendition.Conversely, if playback and/or network conditions improve, the computingdevice 171 may switch to a higher bitrate rendition. The transcoder(s)155 may generate key frame aligned portions for the adaptive streamingrenditions, so that switching to a lower bitrate or higher bitraterendition appears “seamless” (e.g., does not result in noticeable visualglitches or dropped frames at a playback device, such as the computingdevice 171, the television/set-top box 172, the smartphone 173, or thetablet computer 174).

Thus, during an adaptive streaming session, the media server 150 mayreceive a request 130 from the computing device 171 for a particularportion of a particular rendition (e.g., bitrate) of the VOD item. Uponreceiving the request 130, the media server 150 may check whether therequested portion is part of the stored rendition 110. If so, the mediaserver 150 may respond to the request 130 by retrieving the requestedportion from the non-volatile storage 158 and transmitting the requestedportion to the computing device 171. If the requested portion is part ofa different rendition, the transcoder(s) 155 may generate the requestedportion on the fly by transcoding a corresponding portion of the storedrendition 110. The requested portion of the requested rendition and thecorresponding portion of the stored rendition 110 may have the samestart and end frame numbers, the same start and end times, the sameportion numbers or portion identifiers, etc. The transcoder(s) 155 maygenerate a portion 161 on the fly, and the generated portion 161 may betransmitted to the computing device 171 in response to the request 130.In a particular embodiment, sending the generated portion 161 to thecomputing device includes encoding and/or encapsulating the generatedportion in accordance with the adaptive streaming protocol being used bythe computing device 171 (e.g., HLS, HDS, smooth streaming, MPEG-DASH,etc.). As additional adaptive streaming requests are received from thecomputing device 171 for the same or other renditions of the VOD item,the transcoder(s) 155 may generate the additional requested portions onthe fly as needed.

In a particular embodiment, the media server 150 may include a cache157.

For example, the cache 157 may be implemented using random access memory(RAM), disk-based memory, a file system-based cache, or any combinationthereof, at the media server 150. When the media server 150 includes thecache 157, the transcoder(s) 155 may store generated portions of one ormore renditions of VOD items in the cache 157. A cached portion may bere-used if the same portion (of the same rendition) is subsequentlyrequested by the computing device 171 or another device. In the exampleof FIG. 1, the cache 157 stores a cached portion 162. It should be notedthat the illustration of a single cached portion is for example only.The cache 157 may store multiple cached portions multiple renditions ofmultiple VOD items. In a particular embodiment, the cached portion 162is stored in a format that is independent of the available outputprotocols (e.g., HLS, HDS, smooth streaming, MPEG-DASH, etc.). Forexample, the cached portion 162 may be stored in a fragmented MPEG-4part 14 (MP4) format. Storing the cached portion 162 in the fragmentedMP4 format may enable the cached portion 162 to be encoded/encapsulatedusing any of the supported output protocols. Cached portions may beremoved from the cache 157 in accordance with a cache replacement policy(e.g., least recently used (LRU), least frequently used (LFU), etc.).

When the media server 150 includes the cache 157, responding to therequest 130 may include checking the cache 157 to determine if therequested portion is in the cache 157. If the requested portion is inthe cache, the media server 150 may transmit the cached portion to thecomputing device 171, which may take less time than generating therequested portion on the fly and transmitting the generated portion tothe computing device 171. However, if the requested portion is not inthe cache 157, the transcoder(s) 155 may generate the requested portion(as described above) and the generated portion may be stored in thecache 157 and sent to the requesting device.

In a particular embodiment, instead of storing the high-qualityrendition 110 of the VOD item, the media server 150 may retrieveportions of the high-quality rendition 110 of the VOD item from a remotedevice as needed, as illustrated at 141. For example, the media server150 may retrieve the rendition 110 (or portions thereof) from a VODdatabase or content server 140. VOD items may be retrieved via HTTP ornetwork file system (NFS)-mounted disk.

The described techniques may also be used to generate and transmitmultiple renditions of VOD items on the fly from the media server 150 toother servers 180. For example, the media server 150 may transmitgenerated renditions to another media server 181 or to a server (e.g.,an edge server) of a content delivery network (CDN) 182. In alternateembodiments, more than four or less than four renditions may betransmitted. To illustrate, VOD access through the CDN 182 may be set upusing a pull through caching mechanism. The CDN 182 may include one ormore edge HTTP caching servers. If a cache miss for requested contentoccurs at a caching server, the caching server may pull the requestedcontent from the media server 150, which acts as an origin server. Themedia server 150 may perform transcoding to generate the requestedcontent.

In a particular embodiment, the media server 150 may support dynamicupdates to transcoding parameters. For example, a user may edit thetranscoding template(s) 156 or install/upload updated transcodingtemplate(s) 157 to the media server 150. The updated transcodingtemplate(s) 157 may include one or more updated transcoding parametersthat describe an updated rendition of a VOD item. For example, theupdated transcoding template(s) 157 may indicate that a bitrate of arendition of “medium quality” is to be increased from 500 kilobits persecond to 550 kilobits per second. In response to a subsequent requestfor a portion of the “medium quality” rendition, the transcoder(s) 155may generate the portion based on the updated transcoding parameter(s)(e.g., at a bitrate of 550 kilobits per second). Any cached portionscorresponding to the “old” rendition (e.g., encoded at 500 kilobits persecond) may be removed from the cache 157 during normal operation, inaccordance with the cache replacement policy in effect. Alternately, aone-time purge operation may be performed to identify and delete anycached portions corresponding to the old rendition.

The system 100 of FIG. 1 may thus enable on the fly generation of VODrenditions for adaptive streaming. It will be appreciated that bygenerating requested portions of VOD renditions on the fly, the system100 of FIG. 1 may reduce the amount of storage space and the number offiles involved in implementing adaptive streaming for VOD items.

To illustrate, a content provider (e.g., television or movie studio) mayown a content library of files that have bitrates that are too high tostream to users over the Internet or cellular networks. Without accessto the on the fly transcoding system 100 of FIG. 1, the need to convertand store multiple renditions of each file may represent a significantbarrier that prevents the content provider from monetizing the contentlibrary (e.g., by charging fees for adaptive streaming of the content).The content provider may use the system 100 of FIG. 1 to make thelibrary of content available for adaptive streaming without having topre-convert and pre-store additional renditions of the content.

As another example, a user or content provider may have multimedia in alegacy format that is incompatible with adaptive streaming protocols.The system 100 of FIG. 1 may be used to ingest such legacy media and tomake the legacy media available for adaptive streaming withoutpre-converting or pre-storing additional renditions of the media.

FIG. 2 is a diagram to illustrate a particular example (designated 200)of the transcoding template(s) 156 of FIG. 1. As shown in FIG. 2, thetranscoding templates 200 may include transcoding settings for aplurality of VOD stream renditions.

For example, in FIG. 2, the transcoding templates 200 include parametersfor three different renditions 210, 220, and 230. The first rendition210 and the second rendition 220 correspond to audio-video content andthe third rendition 230 corresponds to audio only content. Eachrendition may be enabled or disabled. Renditions that are enabled areavailable for adaptive streaming (e.g., included in the manifest 120 ofFIG. 1). In the example of FIG. 2, the first rendition 210 and thesecond rendition 220 are enabled, whereas the third rendition 230 isdisabled. Each rendition 210, 220, and 230 may have a rendition name(e.g., used for logging) and a stream name that is programmaticallygenerated, as shown. For example, in accordance with the transcodingparameters 200 of FIG. 2, if an input stream is named “media,” streamnames corresponding to the renditions 210, 220, and 230, will be“media_(—)720p,” “media_(—)240p,” and “media_aac,” respectively.

Transcoding parameters for a stream rendition may include a transcoderidentifier (e.g., an identifier of one of the transcoder(s) 155 of FIG.1). For example, both the 720p rendition 210 and the 240p rendition 220include a transcoder identifier of “default” (e.g., non-hardwareaccelerated). In a particular embodiment, the media server 150 may alsoinclude hardware-accelerated transcoders that utilize processorinstruction sets having instructions specific to graphics/videoprocessing operations. Transcoding parameters may also include agraphics processing unit (GPU) identifier (ID). For example, in mediaservers including multiple GPUs, different GPUs may be assigned toperform hardware-accelerated transcoding for different renditions.

Transcoding parameters may further include video parameters, such as avideo bitrate, a frame size, a frame fit, a frame rate, a video CODEC,and a key frame interval. In FIG. 2, the video bitrate is expressed inbits per second and the frame size is expressed as HEIGHT×WIDTHresolution in pixels. The frame fit may indicate how source video is tobe positioned and/or scaled within the frame size. In a particularembodiment, the frame fit may be “Letterbox” (i.e., maintain aspectratio and scale source video to fit frame size while adding black barsas necessary), “Fit-Height” (i.e., adjust the width to fit the specifiedheight while maintaining aspect ratio), “Fit-Width” (i.e., adjust theheight to fit the specified width while maintaining aspect ratio),“Crop” (i.e., maintain aspect ratio and scale to fit frame size bycropping), “Stretch” (i.e., stretch the video to fit the frame size) or“Match Source” (i.e., maintain frame width and height). The frame ratemay be expressed in frames per second (fps). In a particular embodiment,supported video CODECs may include “H.264,” “H.263,” “Pass-Through”(i.e., do not transcode using a video CODEC) and “Disable” (i.e.,disable video in the output stream). When the key frame interval is“Follow Source,” the output stream includes key frames (e.g., I-frames)at the same interval as the source stream. When the key frame intervalis a number N, the output stream includes key frames every N frames.

Transcoding parameters may also include audio parameters, such as anaudio CODEC, an audio sample frequency in hertz (Hz), a number of audiochannels, and an audio bitrate in bits per second. In a particularembodiment, the audio CODEC may be “AAC,” “Pass-Through,” or “Disable.”In a particular embodiment, the number of audio channels may be 1 (i.e.,mono audio), 2 (i.e., stereo audio), 5.1 (i.e., five surround channelsand one bass channel), or 7.1 (i.e., seven surround channels and onebase channel).

It should be noted that although two renditions are enabled in FIG. 2,this is an example only. In alternate embodiments, more than two or lessthan two renditions may be enabled (e.g., available) for adaptivestreaming. For example, the transcoding templates 200 may includetranscoding parameters for a 720p rendition (e.g., for high-bandwidthdevices, such as set-top boxes), a 360p rendition (e.g., formedium-bandwidth devices, such as desktop/laptop computers), a 240prendition (e.g., a low/medium-bandwidth profile for desktop/laptopcomputers or mobile devices), a 160p rendition (e.g., for low-bandwidthmobile devices), etc.

When a request is received for a portion of an enabled rendition, therequested portion may be generated on the fly using the transcodingparameters corresponding to the rendition. For example, if a request fora portion of the 240p rendition 220 is received, the portion generatedby the transcoder(s) 155 of FIG. 1 may have a bitrate of 350 kilobitsper second, may be encoded using H.264 encoding, and may have aresolution of 320×240.

FIG. 2 thus illustrates an ability to define transcoding parameters formultiple stream renditions using one or more transcoding templates 200.

FIG. 3 is a flowchart to illustrate a particular embodiment of a method300 of performing on the fly transcoding of VOD content for adaptivestreaming. In an illustrative embodiment, the method 300 may beperformed by the media server 150 of FIG. 1.

The method 300 includes receiving, at a media server having access to asingle rendition of a video on demand item, a request from a computingdevice for a portion of a particular rendition of a plurality ofrenditions of the video on demand item that are available for adaptivestreaming, at 302. Each of the plurality of renditions has a distinctbitrate. For example, in FIG. 1, the media server 150 may receive therequest 130 from one of the playback devices 170, such as the computingdevice 171, the television/set-top box 172, the smartphone 173, or thetablet computer 174. To illustrate, the plurality of availablerenditions may include the 720p rendition 210 of FIG. 2 and the 240prendition 220 of FIG. 2, and the request 130 may be for a portion of the720p rendition 210 of FIG. 2.

The method 300 may also include, in response to the request, generatingthe requested portion of the particular rendition of the video on demanditem by transcoding a corresponding portion of the accessible renditionof the video on demand item, at 304. For example, in FIG. 1, thetranscoder(s) 155 may generate the requested portion 161 on the flybased on a corresponding portion of the stored rendition 110. Thecorresponding portion may be identified as having the same start/endframe numbers, start/end times, or portion number/identifier as therequested portion. The generated portion of the 720p rendition 210 ofFIG. 2 may have a 1.3 megabit per second bitrate, a 1280×720 resolution,a 24 frames per second frame rate, etc., as indicated in FIG. 2.

The method 300 may further include sending the generated portion to thecomputing device, at 306. For example, in FIG. 1, the media server 150may send the generated portion 161 to the computing device 171.

The method 300 of FIG. 3 may thus enable on the fly generation of VODrenditions for adaptive streaming Generating requested portions of VODrenditions on the fly may reduce the amount of storage space and thenumber of files involved in implementing adaptive streaming for VODitems.

FIG. 4 is a flowchart to illustrate another particular embodiment of amethod 400 of performing on the fly transcoding of VOD content foradaptive streaming. In an illustrative embodiment, the method 400 may beperformed by the media server 150 of FIG. 1.

The method 400 may include sending, from a media server to a computingdevice, information describing a plurality of renditions of a video ondemand item that are available for adaptive streaming, at 402. Each ofthe plurality of renditions may have a distinct bitrate. The pluralityof renditions may also differ in other aspects, such as frame size,video CODEC, audio CODEC, etc. The information describing the availablerenditions may be included in an adaptive streaming manifest and thevideo on demand item may include audio-only, video-only, or audio-videocontent. For example, in FIG. 1, the media server 150 may send themanifest 120 to the computing device 171.

The method 400 may also include receiving, at the media server, arequest from the computing device for a portion (e.g., chunk and/orgroup of pictures) of a particular rendition of a plurality ofrenditions of the video on demand item, at 404. The media server storesa single rendition of a video on demand item. Alternately, the mediaserver has access to the single rendition of the video on demand item(e.g., from a remote VOD database or content server). For example, inFIG. 1, the media server 150 may receive the request 130, where themedia server stores the single rendition 110 of the VOD item or hasaccess to the single rendition 110 of the VOD item stored at the VODdatabase/content server 140.

The method 400 may also include determining whether the requestedportion is in the stored rendition, at 406. When the requested portionis in the stored rendition, the method 400 may include selecting aportion retrieved from the stored rendition for sending to the computingdevice at 408. For example, in FIG. 1, when the requested portion is inthe stored rendition 110, the media server 150 may retrieve therequested portion from the stored rendition 110. The portion of thestored rendition 110 that corresponds to the requested portion may beidentified based on start/end frame numbers, start/end times, or aportion number/identifier of the requested portion included in therequest 130. To illustrate, a media player or playback device mayrequest a particular portion of a VOD asset with encoding parametersbased on one of the renditions described in the manifest 120 (i.e., themedia player or playback device may be restricted to requesting portionsthat conform to one of the renditions in the manifest 120).

When the requested portion is not in the stored rendition, the method400 may include determining whether the requested portion is cached, at410. When the requested portion is cached, the method 400 may includeselecting a portion retrieved from a cache for sending to the computingdevice at 412. For example, in FIG. 1, when the requested portion isstored in the cache 157, the media server 150 may retrieve the requestedportion (e.g., the portion 162) from the cache 157. The cache 157 may beindexed by rendition and portion (e.g., portion start/end frame numbers,start/end times, or portion number/identifier).

When the requested portion is not cached, the method 400 may includegenerating the requested portion by transcoding a corresponding portionof the stored rendition, at 414, caching the generated portion, at 416,and selecting the generated portion for sending to the computing device,at 418. For example, in FIG. 1, when the requested portion is notcached, the transcoder(s) 155 may generate the requested portion (e.g.,the portion 161) on the fly from a corresponding portion of the storedrendition 110. In a particular embodiment, the generated portion iscached for subsequent retrieval in a protocol-independent format, suchas fragmented MP4.

The method 400 may include sending the selected portion to the computingdevice based on a streaming protocol that is compatible with thecomputing device (e.g., HLS, HDS, smooth streaming, and/or MPEG-DASH),at 420. For example, in FIG. 1, the media server 150 may send theportion 161 or the portion 162 to the computing device 171 (or anotherone of the playback devices 170). In a particular embodiment, the mediaserver 150 may fragment and encapsulate the portion 161 or the portion162 based the streaming protocol to be used.

In accordance with various embodiments of the present disclosure, one ormore methods, functions, and modules described herein may be implementedby software programs executable by a computer system. Further,implementations can include distributed processing, component/objectdistributed processing, and/or parallel processing.

Particular embodiments can be implemented using a computer systemexecuting a set of instructions that cause the computer system toperform any one or more of the methods or computer-based functionsdisclosed herein. A computer system may include a laptop computer, adesktop computer, a server computer, a mobile phone, a tablet computer,a set-top box, a media player, one or more other computing devices, orany combination thereof. The computer system may be connected, e.g.,using a network, to other computer systems or peripheral devices. Forexample, the computer system or components thereof can include or beincluded within any one or more of the media server 150 of FIG. 1, theVOD database/VOD content server 140 of FIG. 1, the desktop/laptopcomputing device 171 of FIG. 1, the TV/set-top box 172 of FIG. 1, thesmartphone 173 of FIG. 1, the tablet computer 174 of FIG. 1, the mediaserver/stream relay server 181 of FIG. 1, a server (e.g., edge server)of the CDN 182 of FIG. 1, or any combination thereof.

In a networked deployment, the computer system may operate in thecapacity of a server or as a client user computer in a server-clientuser network environment, or as a peer computer system in a peer-to-peer(or distributed) network environment. The term “system” can include anycollection of systems or sub-systems that individually or jointlyexecute a set, or multiple sets, of instructions to perform one or morecomputer functions.

In a particular embodiment, the instructions can be embodied in anon-transitory computer-readable or a processor-readable medium. Theterms “computer-readable medium” and “processor-readable medium” includea single medium or multiple media, such as a centralized or distributeddatabase, and/or associated caches and servers that store one or moresets of instructions. The terms “computer-readable medium” and“processor-readable medium” also include any medium that is capable ofstoring a set of instructions for execution by a processor or that causea computer system to perform any one or more of the methods oroperations disclosed herein. For example, a computer-readable orprocessor-readable medium or storage device may include random accessmemory (RAM), flash memory, read-only memory (ROM), programmableread-only memory (PROM), erasable programmable read-only memory (EPROM),electrically erasable programmable read-only memory (EEPROM), registers,a hard disk, a removable disk, a disc-based memory (e.g., compact discread-only memory (CD-ROM)), or any other form of storage medium ordevice.

In a particular embodiment, a method includes receiving, at a mediaserver, a request from a computing device for a portion of a particularrendition of a plurality of renditions of a video on demand item thatare available for adaptive streaming. Each of the plurality ofrenditions has a distinct bitrate. The media server has access to asingle rendition of the video on demand item. The method also includes,in response to the request, generating the requested portion of theparticular rendition of the video on demand item by transcoding acorresponding portion of the accessible rendition of the video on demanditem. The method further includes sending the generated portion to thecomputing device.

In another particular embodiment, a media server includes a processorand a memory storing a single rendition of a video on demand item. Themedia server also includes a network interface configured to receive arequest from a computing device for a portion of a particular renditionof a plurality of renditions of the video on demand item that areavailable for adaptive streaming. Each of the plurality of renditionshas a distinct bitrate. The network interface is also configured to sendthe requested portion to the computing device. The media server furtherincludes a transcoder executable by the processor to, in response to therequest, generate the requested portion of the video on demand item bytranscoding a corresponding portion of the stored rendition of the videoon demand item.

In another particular embodiment, a computer-readable storage devicestores instructions that, when executed by a computer, cause thecomputer to receive, at a media server, a request from a computingdevice for a portion of a particular rendition of a plurality ofrenditions of the video on demand item that are available for adaptivestreaming Each of the plurality of renditions has a distinct bitrate.The media server has access to a single rendition of the video on demanditem. The instructions are also executable to cause the computer to,when the requested portion is part of the stored rendition, send aportion retrieved from the stored rendition to the computing device inresponse to the request. The instructions are further executable by theprocessor to, when the requested portion is not part of the storedrendition and is stored in a cache of the media server, send a portionretrieved from the cache to the computing device in response to therequest. The instructions are executable by the processor to, when therequested portion is not stored in the cache at the media server,generate the requested portion by transcoding a corresponding portion ofthe accessible rendition and send the generated portion to the computingdevice in response to the request.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those of skill in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope of the disclosure.Accordingly, the disclosure and the figures are to be regarded asillustrative rather than restrictive.

Although specific embodiments have been illustrated and describedherein, it should be appreciated that any subsequent arrangementdesigned to achieve the same or similar purpose may be substituted forthe specific embodiments shown. This disclosure is intended to cover anyand all subsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

The Abstract of the Disclosure is submitted with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. In addition, in the foregoing Detailed Description, variousfeatures may be grouped together or described in a single embodiment forthe purpose of streamlining the disclosure. This disclosure is not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter may bedirected to less than all of the features of any of the disclosedembodiments.

The above-disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe scope of the present disclosure. Thus, to the maximum extent allowedby law, the scope of the present disclosure is to be determined by thebroadest permissible interpretation of the following claims and theirequivalents, and shall not be restricted or limited by the foregoingdetailed description.

What is claimed is:
 1. A method comprising: receiving, at a mediaserver, a request from a computing device for a portion of a particularrendition of content that is available for adaptive streaming, whereinthe request is received while the media server has access to a singlerendition of the content; when the portion is part of the singlerendition, sending the portion retrieved from the single rendition tothe computing device in response to the request; when the portion is notpart of the single rendition: generating the portion by transcoding acorresponding portion of the single rendition of the content; storingthe generated portion in a cache of the media server; and sending thegenerated portion to the computing device in response to the request;and removing portions of one or more outdated renditions from the cachewhile maintaining the generated portion in the cache.
 2. The method ofclaim 1, further comprising when the portion is not part of the singlerendition and prior to generating the portion, determining whether theportion is stored in the cache.
 3. The method of claim 2, whereingenerating the portion occurs in response to determining that theportion is not stored in the cache.
 4. The method of claim 1, whereinsending the generated portion to the computing device includes sendingthe generated portion based on a streaming protocol that is compatiblewith the computing device.
 5. The method of claim 4, wherein thestreaming protocol includes: HTTP dynamic streaming (HDS), smoothstreaming, or motion picture experts group (MPEG) dynamic adaptivestreaming over HTTP (MPEG DASH).
 6. The method of claim 1, wherein thestored portion is in a format that is independent of a plurality ofoutput protocols used to send the generated portion to one or morerequesting devices.
 7. The method of claim 6, wherein the formatcomprises a fragmented motion picture experts group-4 part 14 (MP4)format.
 8. The method of claim 1, wherein the generated portioncomprises a group of pictures that includes an intra-coded frame(I-frame) and one or more additional frames that include differenceinformation relative to the I-frame.
 9. The method of claim 1, furthercomprising, in response to a subsequent request for the generatedportion: retrieving the generated portion from the cache; and sendingthe retrieved portion in response to the subsequent request.
 10. Themethod of claim 1, further comprising, prior to receiving the request,sending information to the computing device, the information describinga plurality of renditions of the content that are available for adaptivestreaming.
 11. The method of claim 1, wherein the request includesinformation specifying the portion by a portion number/identifier, aframe start number and end number, a portion start time and end time, orany combination thereof.
 12. The method of claim 1, wherein the singlerendition of the content is stored in a non-volatile memory of the mediaserver.
 13. The method of claim 1, wherein a plurality of renditions ofthe content are available for adaptive streaming from the media server,and wherein the plurality of renditions and one or more transcodingparameters are identified by a transcoding template stored at the mediaserver.
 14. The method of claim 13, wherein the one or more transcodingparameters include, for a rendition of the content, a key frame intervalof the rendition, a frame size of the rendition, a frame rate of therendition, information regarding one or more coders/decoders (CODECs)associated with the rendition, an audio sample frequency of therendition, and a number of audio channels of the rendition.
 15. Themethod of claim 1, further comprising: receiving an updated transcodingtemplate at the media server, the updated transcoding template includingone or more updated transcoding parameters for an updated rendition ofthe content; and in response to a subsequent request for a portion ofthe updated rendition, generating the portion of the updated renditionbased on the one or more updated transcoding parameters.
 16. A mediaserver comprising: a processor; a memory storing a single rendition ofcontent; a network interface configured to: receive a request from acomputing device for a portion of a particular rendition of the contentthat is available for adaptive streaming, wherein the request isreceived while the media server has access to the single rendition ofthe content; when the portion is part of the single rendition, send theportion retrieved from the single rendition to the computing device inresponse to the request; and when the portion is not part of the singlerendition, send a generated portion to the computing device in responseto the request; and a transcoder executable by the processor to: inresponse to the request, generate the portion of the content bytranscoding a corresponding portion of the stored single rendition ofthe content; store the generated portion in a cache of the media server;and remove portions of one or more outdated renditions from the cachewhile maintaining the generated portion in the cache.
 17. The mediaserver of claim 16, wherein the cache is configured to store thegenerated portion for subsequent retrieval in response to a subsequentrequest for the generated portion, wherein the cache comprisesdisk-based memory, random access memory (RAM), or a combination thereof.18. The media server of claim 16, wherein: the transcoder is configuredto simultaneously generate a plurality of renditions of the-content fromthe stored single rendition of the content, and the network interface isfurther configured to simultaneously send each of the plurality ofrenditions of the content to another media server, a stream relayserver, a server associated with a content delivery network (CDN), orany combination thereof.
 19. A computer-readable storage device storinginstructions that, when executed by a computer, cause the computer to:receive, at a media server, a request from a computing device for aportion of a particular rendition of content that is available foradaptive streaming, wherein the request is received while the mediaserver has access to a single rendition of the content; when the portionis part of the single rendition, send the portion retrieved from thesingle rendition to the computing device in response to the request;when the portion is not part of the single rendition: generate theportion by transcoding a corresponding portion of the single renditionof the content; store the generated portion in a cache of the mediaserver; and send the generated portion to the computing device inresponse to the request; and remove portions of one or more outdatedrenditions from the cache while maintaining the generated portion in thecache.
 20. The computer-readable storage device of claim 19, wherein thecache is configured to store the generated portion for subsequentretrieval in response to a subsequent request for the generated portion,wherein the cache comprises disk-based memory, random access memory(RAM), or a combination thereof.